The present invention relates to expansion valves of the type employed for controlling flow of liquid refrigerant at relatively high pressure to enable the refrigerant to be circulated at a substantially reduced pressure through a heat exchanger or evaporator over which is directed a flow of air for cooling a compartment such as the passenger compartment of a motor vehicle. Such expansion valves are well known in the art and one type of known expansion valve is controlled by a thermally responsive liquid filled capsule which utilizes the expansion and contraction of the liquid fill in the capsule to move a diaphragm which movement in turn operates a valve member for controlling flow through the valve from a minimum bleed flow to a maximum flow. Furthermore, it is also known to provide a supplemental solenoid operated shut-off valve in the inlet of the expansion valve for permitting complete shut-off of the flow remotely by an electrical control.
However, problems have been encountered in the aforesaid type of valve inasmuch as flow noise has been generated within the valve which has been found to be prohibitive from the standpoint of annoyance to the occupants of the passenger compartment of the motor vehicle. Efforts to muffle the sound in the refrigerant conduits and in the mounting of the valve body to the vehicle structure have generally proven unsuccessful. Therefore, it has long been desired to provide a simple and low cost, but effective way of reducing or minimizing the flow noise of refrigerant flowing from the high pressure inlet side to a substantially reduced lower pressure outlet in a refrigerant flow control or expansion valve.